Optimum predetection diversity receiving system Patent

Development of optimum pre-detection diversity combining receiving system adapted for use with amplitude modulation, phase modulation, and frequency modulation system

Optical Variability of the Black Hole Candidate GX339-4 (X1659-487, V821 Ara) - Limits on Periodic Modulation

We present results of extensive CCD optical photometry (over 1000 frames representing ~150 hr of integration time) of the optical counterpart of the X-ray source GX339–4 obtained during the high (soft) state. The source was seen to be significantly variable. We do not, however, detect any periodic modulation with semi-amplitude greater than ~0.03 mag for periods less than ~0.5 day or semi-amplitude greater than ~0.07 mag for longer periods. An optical spectrum obtained shortly after GX339–4 made a transition from a ‘low’ to a ‘high’ state is also presented and compared with previous results. The width of the He IIλ4686 emission line in the spectrum implies that GX339–4 does not have an unusually low inclination angle and we therefore conclude that the orbital period of GX339–4 is probably longer than ~0.5 day

The 14.8-h Orbital Period of GX339-4

We present the results of photometric observations of the black hole candidate GX339-4, obtained while the system was in an \u27off\u27 state. We show that a 14.8-h modulation was present, and provide evidence for a similar periodicity in the \u27high\u27 state from a reanalysis of previously published photometry and spectroscopy. The presence of the same period in both states implies that it is likely to be the orbital period of the system. The spectroscopy analysis provides evidence for an apparent change in the systemic velocity of the system. The amplitude of the observed radial velocity variations, however, permits only crude limits to be placed on the mass of the compact object. Only absorption-line spectroscopy of the secondary in the \u27off\u27 state will provide a convincing mass determination

Power supply for the LBL 40 keV neutral beam source

A 20 keV, 50 Amp, 10 millisec pulse D$sup 0$ Neutral Beam Source at the Lawrence Berkeley Laboratory that serves as the prototype for 12 similar sources now in operation on the 2XIIB Mirror Machine at the Lawrence Livermore Laboratory has been recently upgraded to operate at 40 keV. The system of electronically regulated and controlled power supplies that drive the Source is described. (auth

Human preferences for sexually dimorphic faces may be evolutionarily novel

This article has been made available through the Brunel Open Access Publishing Fund.A large literature proposes that preferences for exaggerated sex typicality in human faces (masculinity/femininity) reflect a long evolutionary history of sexual and social selection. This proposal implies that dimorphism was important to judgments of attractiveness and personality in ancestral environments. It is difficult to evaluate, however, because most available data come from largescale, industrialized, urban populations. Here, we report the results for 12 populations with very diverse levels of economic development. Surprisingly, preferences for exaggerated sex-specific traits are only found in the novel, highly developed environments. Similarly, perceptions that masculine males look aggressive increase strongly with development, specifically, urbanization. These data challenge the hypothesis that facial dimorphism was an important ancestral signal of heritable mate value. One possibility is that highly developed environments provide novel opportunities to discern relationships between facial traits and behavior by exposing individuals to large numbers of unfamiliar faces, revealing patterns too subtle to detect with smaller samples

Maximising Social Interactions and Effectiveness within Distance Learning Courses: Cases from Construction

Advanced Internet technologies have revolutionised the delivery of distance learning education. As a result, the physical proximity between learners and the learning providers has become less important. However, whilst the pervasiveness of these technological developments has reached unprecedented levels, critics argue that the student learning experience is still not as effective as conventional face-to-face delivery. In this regard, surveys of distance learning courses reveal that there is often a lack of social interaction attributed to this method of delivery, which tends to leave learners feeling isolated due to a lack of engagement, direction, guidance and support by the tutor. This paper defines and conceptualises this phenomenon by investigating the extent to which distance-learning programmes provide the social interactions of an equivalent traditional classroom setting. In this respect, two distance learning case studies were investigated, covering the UK and Slovenian markets respectively. Research findings identified that delivery success is strongly dependent on the particular context to which the specific distance learning course is designed, structured and augmented. It is therefore recommended that designers of distance learning courses should balance the tensions and nuances associated with commercial viability and pedagogic effectiveness

Photometry and Spectroscopy of KS Ursae Majoris during Superoutburst

We report photometric and spectroscopic observations of the SU UMa-type dwarf novae, KS Ursae Majoris, during its 2003 February superoutburst. Modulations with a period of $0.07017\pm0.00021$ day, which is 3.3% larger than the orbital period, have been found during the superoutburst and may be positive superhumps. A maximum trough-to-peak amplitude of around 0.3 magnitude is determined for this superhump. The spectra show broad, absorption-line profiles. The lines display blue and red troughs which alternate in depth. The radial velocity curve of the absorption wings of H$\beta$ has an amplitude of $40\pm11$ km s$^{-1}$ and a phase offset of $0.12\pm0.03$. The $\gamma$ velocity of the binary is $3\pm9$ km s$^{-1}$ and varies on an order of 50 km s$^{-1}$ from day to day. From another clear evidence for a precessing eccentric disk, we obtain a solution to an eccentric outer disk consistent with theoretical works, which demonstrates the validity of the relation between superhumps and tidal effects. The inner part of the disk is also eccentric as evidenced by asymmetric and symmetric wings in the lines. Therefore, the whole disk is eccentric and the variation of $\gamma$ velocity and the evolutionary asymmetric line profiles could be criterions for an precessing eccentric accretion disk.Comment: 12 pages, 8 figures, accpeted for publication in A

On the orbital period of the cataclysmic variable V592 Herculis

We present a spectroscopic study of the long-recurrence-time dwarf nova V592 Herculis based on observations obtained during its August 1998 superoutburst. From the analysis of the radial velocities of the Halpha emission line we find a most likely orbital period of 85.5 +- 0.4 minutes, but the 91.2 +- 0.6 minutes alias cannot be completely discarded. Both periods imply a very small period excess and supports the brown-dwarf like nature of the secondary star.Comment: 4 pages, 5 figures, accepted for publication in Astronomy and Astrophysic

Optical Spectral Monitoring of XTE J1118+480 in Outburst: Evidence for a Precessing Accretion Disk?

We present spectroscopic observations of the X-ray transient XTE J1118+480 acquired during different epochs following the 2000 March outburst. We find that the emission line profiles show variations in their double-peak structure on time scales longer than the 4.1 hr orbital period. We suggest that these changes are due to a tidally driven precessing disk. Doppler imaging of the more intense Balmer lines and the HeII 4686 line shows evidence of a persistent region of enhanced intensity superposed on the disk which is probably associated with the gas stream, the hotspot or both. We discuss the possible origins of the optical flux in the system and conclude that it may be due to a viscously heated disk.Comment: 15 pages, 8 figures, accepted by Ap

A Study of Brain Networks Associated with Swallowing Using Graph-Theoretical Approaches

Functional connectivity between brain regions during swallowing tasks is still not well understood. Understanding these complex interactions is of great interest from both a scientific and a clinical perspective. In this study, functional magnetic resonance imaging (fMRI) was utilized to study brain functional networks during voluntary saliva swallowing in twenty-two adult healthy subjects (all females, 23.1±1.52 years of age). To construct these functional connections, we computed mean partial correlation matrices over ninety brain regions for each participant. Two regions were determined to be functionally connected if their correlation was above a certain threshold. These correlation matrices were then analyzed using graph-theoretical approaches. In particular, we considered several network measures for the whole brain and for swallowing-related brain regions. The results have shown that significant pairwise functional connections were, mostly, either local and intra-hemispheric or symmetrically inter-hemispheric. Furthermore, we showed that all human brain functional network, although varying in some degree, had typical small-world properties as compared to regular networks and random networks. These properties allow information transfer within the network at a relatively high efficiency. Swallowing-related brain regions also had higher values for some of the network measures in comparison to when these measures were calculated for the whole brain. The current results warrant further investigation of graph-theoretical approaches as a potential tool for understanding the neural basis of dysphagia. © 2013 Luan et al